Telephone testing system.



11. s. WINSTON.

' TELEPHONE TESTING SYSTEM. 1 APPLIOATION FILED Mus, 1907.

983,966, Patented Feb. 14,1911.

sf- 1 1 Q and improve systems ofthis character suci that by theluse of simple and inexpensive apparatus a My invention-is illustrated in the accomi so far describedcomprises n o"part of my To all whom it may concern:

a citizen of the United States residing in "UNITED sTATEsPATEN OFFICE.

CHARLES S. WINSTON, OF CHICAGO, ILLINOIS, ASSIQNOR TO KELLOGG SWITCHBOARD AND SUPPLY COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

TELEPHONE TESTING SYSTEM.

Be it known that I, CHARLES S. TINSTON,

Chicago, county of Cook, and State of Illinois have invented certain new and useful Improvements in Telephone Testing Syste1ns,'.of which the following is a specificationf My invention relates to telephone testing systems such as are used at the central ofiice of an exchange for obtaining theidle or busy" condition of the telephone lines be-fore completing a, conversational connection there- The object of my invention is to simplify positive indication of the condition of the ine will'be given to-the operator'inaneflicient ma'nne panying drawing in which shown in its normal condition. The calling and called subscribers stations are represented at the right and left' of the drawing, these stations being equip ed with similar apparatus at .thecent-ral 0 cc, the apparatus of the called line being designated by figures having the suffix Station 1 is provided with the ringer or annundiator 2, and coiidenser 3 in a permanent bridge of the line conductors, and with the transmitter 4 and receiver 5 in a bridge normally maintained open by contacts of the hook switch 6. This substation is connected with the centralcflice by line wires 7 and 8, the conductor Tbeingconnected with the ground pole. of battery-A through the o utside contacts of the cut-off relay 9fthe con doctor 8 being connected through the other outside contacts of'relay 9 and the coil of the line'relay 10 with the live pole of battery A. Line relay 10 controls contacts in the circuit of the line signal 11- and battery A. The line .is' royided with the usual answering and mu tiple jalcks'ha'vin-g test contacts 12 and tipcontacts 13, thetestcontactsbeing connected with one of the, inside contacts of all apparatus is lay, and the ,tip contacts being connected with'the' other inside contact of relay 9 It is to be understood that'the apparatus present invention, and that any other suitable apparatus nay be substituted therefor.

ing end of th springof the operators Specification of Letters Patent. Patented Feb. 14, 1911. Application filcdJEay't), 1907. Serial No. 372,697.

The cord circuit ada ted for use with this telephone line is provi ed with the terminal plugs .14 and 15, the tip contacts of these plugs being connected with the tip strand 16 and the sleeve contacts being connected with the sleeve strand 17. The tip and sleeve strands contain respectively condensers 18- and 19 and series contacts of the operators ringing key 20. The tip strand also contains the normally open contacts 21-and 22 con- 6 trolled by the sleeve calling supervisory re-' lay 24. The answering end of the'cord circuit is provided with the tip and sleeve relays 25 and 26 connected in a bridge of the talking circuit,-including' the central source of current A, and jointly controlling thecircuit of su tervisory signal 27. .The call- "cord circuit is similar] provided with tip and sleeve relays 28 an 24 in a'simi lar, bridge of the calling end of'the 75. cord circuit, and"sin iilarly controlling the circuit of supervisorysignal 29.-.

The-tip of the calling plug. 15 is normally connected-through the tip-series contacts of the operators ringing key 20 with contact 21 of the supervisory relay 24c, and thence through the normally closed contact 23 and conductor 31 with the normally disconnected auxiliary spring 32 of the operators listening key 33. This spring 32' is adapted to make connection with the contact 34 when the key is actuated, this contact being connected through conductor 35 and the high resistance impedance coil 36 to ground. A branch conductor from conductor 35 con- .90. nects with the condenser 37 and from the other terminalof this condenser through the tertiary winding 38 of the operators induction coil 39 to the liva pole of central-battery A.

The upper spring of the operators listening key. is connected through conductor 40 with the tip strand of the cord circuit at a point to the left-bfethe contacts-21' and 2 2 of the suprvisoryjrelay 2%, while the lower spring is connected directly 'tothe'sleeve strand of the.- cordcircuitmThe lower ringing key 20 is adapted when actuated to connect with con-' tact t2 which conhects with thelivepole ofibattery' A through the non-induct ve .re--

'sist'ance 43, Theftip spring ofthis-ringingkey is adapted .to connect with any suitablesource of ringing current.

In operation, the subscriber'in'charge'of substation'No. 1 removes his receiver from desired number.

its hook, thereby completing the circuit ofline relay 10 and displaying the line signal 11. The operator thereupon inserts her answering plug 14 in the jack of the called line and-1n so doing completes the circuit of her'supervisoryrelay 26 from the live pole of battery througl the coil of that relay, .the,

sleeve of .the plug and jack, and the coil of relav 9 to ground. Relays 2G.and' 9 are thereby actuated, the actuation of relay 9 completing the circuit of supervisory relay over the telephone line. Relays 25 and 26 now being -actuated, the supervisory signal 27 is not displayed, The operator now throws her listening key 33 and inquires the Finding 1. to be the substation desired, the opcratortouches the tip COl'ltilClL of pll'ig 15 to one of the test contacts 12-ass'ociated with the desired line.

If the desired line is' busy, its test contacts will. be in connection with thesleeve'coih tact of another cord circuit and will thereby be at apotential higher'than that of earth. Current will thcrefore flow frmuthe test contact of the jack over the tip of the cord circuit, through the coin-acts 21 and 2510f supervisory relay 24,-- over coiuluctor 3L,

. contacts 32 and of the listening-key 33,

throughconductor to the conniectedterminals of the impedance coil 36- and. the condenser '37: The condenser 37 1s normally fully. charged,- one terminal being connected with the earth pole of battery A through the'impedance coil 36, and the other terminal being connected through the tertiary winding 38 of the operators indue-j the coil 36, of a capacity of condenser-3T and the resistance of the winding 38 of the operators induct-ion co l the most desirable volume of test current may be obtained, and

it has been found possible to vary this volnine between reasonable limits bysiinply ad justing the coil 36. If the desired line is not busy its. test contact will be at'the potential of earth and there will therefore be no discharge of condenser 37 when thetip of the cord is connected with the test contact of the line and the operatorwill receive no signal.

Assuming the desired line to be idle, the operator inserts her calling plugand are by completes a circuit from the live pole of battery A through the coil' of supervisory relay 2 through the sleeve of the plugand jack andthe coil of cut-ofi relay 9' to ground. This actuates relay 9, connecting the limbs 7' and 8 of the telephone line respectively with contacts 13 and 12' of the jacks and also actuates relay 24 which completes the circuit of'supervisory signal 29, displaying that signal. The actuation of relay 2 k also completes the normally broken tip strand of the cord circuit by closing,contacts 21 and 22 and disconnects test conductor 31 by severing contacts 21 and 23. The operator now throws her ring ing key and therebysubstitutes the noninductive resistance 5L3 for the coil of relay 2t and maintains the cjut-ofl relay actuated as before, simultaneously placin ringing current on the tip sidejof the'telepiione line. This ringing current passes through the condenser 3, annuncia'tor'2, back through the hon-inductive resistance 43 and the batter-y A topea-rth. Willem t-l1e' called .'sub--' scribcr answers his call the circuit. is completed'through the-hook switch 4' and over the tip of'the jack and plug through the coil (if supervisory relay 28' to ground; This.actuates relay 2 8 and efifaces the super- \-'isor \"signal 29.. Thesubscribors are new in conversation and all signals at the centraloifice' are eiliaced." \Vhen either subscriber terminates the conversation the supervisory signal'associated with his line is displayed by t-lie'falling-back of the 'tip supe1 'visory relay for his end of thecord clrcuit. \Vhen both supervisory signals 27 and 29 are displayedlthe operator removes herfconnecting plu s and the apparatus assumes its normal con itlon.

It is to be understood that the cord circuit here shown and described isonly to illustrate the application of my testing system to an operative telephone system, an that many other forms of central energy cord nect'ed in abridge bet-ween the poles' of said source, a testing conductor connected to the conductor' connecting said condenser and said impedance coil, and a receiver ind'uctively connected with the winding-of said induct-ion coil for-receiving discharge dis tnrb'ance from said condenser when a busy line is tested, substantially as described.

circuits could be substituted'without inany 2. In a telephone system, the combination with a telephone line having testing contacts at the central office, a testing conductor to'.

connect therewith,.a source of current, an.

impedance coil connected between a pole of said source and said testing conductor, a condenser and an induction coil winding permanently connected in series between said testing conductor and the other pole of said source, and a test receiving device affected bythe change of current in the induction coil winding due to the discharge of said condenser when the test conductor is connected with 'the test ring of a busy line, substantiallyaes described.

3. In a telephone system, the-combination With a telephone line having testing contacts at the central'oiiice, a testing conductor to connect therewith, a source of currcnt,'an operatorsinduction coil, a condenser and a winding of said induct-ion coil permanently serially connected between said testing conductor and a pole of said source, an impedance coil connected between the testing conductor and the other pole of'said source, a test receiving device in the circuit of an other Winding of'said induction coil actuated by the discharge of said condenser when the test'conductor is connected with the test contact of a busy line, substantially as described.

4. A telephone testing system comprising a source of currei'it, an impedance coil, a condenser and a winding of an induction coil in a closed circuit, whereby the condenser is charged, means to complete a circuit in "shunt of the condenser and winding of the induction coil when a busy line is tested, whereby thc'condenser 1s discharged,

a second winding for said induction coil,-

and a receiver connected therewith to detect the discharge of said condenser, substantially as described.

- 5. In a telephone system, thecombination with acord circuithaving a talking strand,

a testing strand connected therewith, a

source of current, an impedance coil, a condenser and an induction coil winding in a series circuit with said source, a terminal of said impedance coil and a terminaLof said condenser being connected with the test 0011-. ductor during testing, a test receiving device, and means whereby said testing con ductor cannot be connected with ,the cord circuit during a com lete connectlon, sub stantially as describe 6. In a telephone system, the combination with a cord circuit havin a talking strand, a testing strand normally isolated therefrom, a source of current, an impedance coil, .a condenser and an induction coil winding in aseries circuit with said source, a terminal of said impedance coil and a terminal of said condenser normally connected with said testconductor, a test receiving'device inductively connected with said induction coil winding, means to connect said test conductor with the cord circuit during testing, and means whereby said testing conductor cannot be connected with a talking strand of the cord circuit during a complete connection, substantially as described.

7. In combination with a telephone connccting circuit, a source of current, an impedance coil, a condenser and a winding of an induction coil permanently connected in a series circuit with said source, and a test conductor having one end connected between said condenser and impedance coil, and adapted to be connected with thctcst contacts'of a line during testing, substantially as described.

Signed byme at Chicago, county of Cook, and State of'Illinois, in the. presence of two witnesses.

oirannns' WINSTON. \Vitnesses Eurrlr F. Ginsu; Cmrrono C. Brannon): 

